Impairment in letter detection in individual subjects, t and p values for the individual contrast between dual task trials with long and short SOA, and talairach coordinates of the ventrolateral prefrontal region in which this contrast was calculated.

*LA showed no BOLD activity in the group ROI (x = −27, y = 26, z = 9). Here, we conducted an individual whole brain contrast between dual task trials with short and long SOA, searched for the peak of activity closest to −27 26 9 and defined it as ROI. To test the robustness of the correlation, we additionally performed the correlation analysis without LA, i.e., based on only eight subjects. The results confirmed the findings of the correlation analysis with nine subjects, r = .7; p<.05.
For all, except one subject, we used the region in left VLPFC revealed previously by the group analysis.